The invention relates to a method for navigating, for example a surgical instrument or an endoscope, in the interior of the body using three-dimensionally visualized structures.
During surgical operations, an attempt is made, as a rule, to make as small a cut as possible through the skin of the patient. Said cut is often just big enough in order to be able to reach the anatomical structure to be treated in the interior of the body with surgical instruments. For this reason, it is difficult for the surgeon and often even impossible to survey optically those anatomical structures of the patient that are relevant to the operation. Even the position, for example, of surgical instruments relative to an anatomical object to be treated is often not visible to the surgeon. For this reason, methods of visualizing structures in the interior of the body for the purpose of navigating such instruments are increasingly gaining in importance.
DE 198 07 884 A1 describes a method for navigating a surgical instrument in the interior of the body. In accordance with this method, a plurality of images are made from various positions and orientations by means of an imaging device and the relative positions and orientations of the images with respect to one another are determined. Then, with the aid of said images, the relative position of an anatomical target object with respect to the surgical instrument is intraoperatively determined and visualized. Both for the precise planning of an operation and for the optical monitoring of the course of the operation, two-dimensional images, such as X-ray images, are as a rule inadequate. There is therefore a requirement to use three-dimensional representations.
Such three-dimensional representations can be generated, for example, by means of computer tomography (CT). Because of the equipment factors and because of the high computational expenditure, CT methods are primarily used to obtain preoperative data. CT methods are therefore unsuitable for an intraoperative visualization, i.e. a visualization taking place during the operation. Furthermore, the high radiation exposure accompanying the CT methods is in many cases undesirable for the patient.
To avoid high radiation exposure, thought can be given to generating the three-dimensional representations needed to plan the operation and to monitor the course of the operation from two or more two-dimensional representations. Such a method is described, for example, in U.S. Pat. No. 4,899,318.